JPH0677112B2 - Optical polarizer cooling device - Google Patents

Description

The present invention relates to an optical deflector cooling device. More specifically, the present invention relates to a device that efficiently releases heat generated by loss of an electric motor when the optical deflector is operated at high speed to cool the optical deflector.

(Prior Art) A conventionally used optical deflector has a hermetically sealed structure as shown in FIG. 5, and only a light deflection window is slightly opened to the outside.

A rotor 6 having a rotary polygon mirror 4 mounted therein is rotatably housed in a housing 2. The main body 8 of the rotor 6 is a pair of bearings 12, 14 mounted on the outer periphery of a fixed shaft 10 standing on the housing 2.
Thus, the fixed shaft 10 is rotatable about the core. The rotary polygon mirror 4 is mounted on the upper surface of the flange 9 of the rotor body 8.
Further, a flat plate-shaped magnet 16 is provided on the lower surface of the flange 9, and the housing 2 is arranged so as to face the magnet 16.
A disk-shaped coil support plate 18 is provided inside. A coil group 20 is arranged on the lower surface of the coil support plate 18. Further, the yoke 22 is fixed to the step portion of the inner wall of the housing so as to face the coil group 20. Reference numeral 24 is a light deflection window provided in the housing 2. Reference numeral 26 is an upper cover of the housing 2.

By energizing the coil group 20, the rotor 6 rotates together with the rotary polygon mirror 4 according to a known operating principle, and the rotary polygon mirror 4 reflects the beam incident from the light deflection window 24, so that so-called light deflection is performed. .

(Problems to be Solved by the Invention) However, the conventional optical deflector has the following problems.

(B) The heat generated in the coil group and the fixed yoke due to the rotation of the rotor due to the closed structure except the light deflection window is confined in the light deflector, limiting the allowable (motor) input. .

(B) The yoke is fixed to the housing, and the loss due to the eddy current increases as the optical deflector rotation speed increases, and it acts as a brake for the optical deflector motor.

(C) When the temperature inside the optical deflector rises, lubricating oil may flow out from the bearings, and because of the closed structure excluding the optical deflecting window, the lubricating oil that has flowed out becomes particulate and the surface of the polygon mirror On the surface of the optical deflector, resulting in deterioration of the performance of the optical deflector.

The present invention aims to solve the above problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides the means described below.

That is, a rotary polygon mirror and a magnet plate are mounted on the upper and lower surfaces of a flange provided on a rotor body rotatably housed in a housing, and a coil support plate having a coil group on the lower surface faces the magnet plate. The rotor is supported by the inner side wall of the housing, and a rotor rotatable with the rotor is provided at the lower end of the rotor body.A group of blades is projectingly provided on the lower surface of the yoke. This is a cooling device for an optical deflector, which is formed by punching and further providing an outflow vent on the bottom surface of the housing in the thrust direction facing the blade group.

(Operation) Now, when the coil group is energized and excited and the rotor rotates in the housing with the fixed shaft as the core based on a known principle, the yoke attached to the lower surface of the rotor body rotates together with the blade group. The rotation of the group causes the air in the housing to flow. The air that has flowed into the housing from the light deflection window or the inflow ventilation port due to the flow action is
Since it flows in the housing and flows out from the outflow ventilation port group to the outside, it cools the components arranged in the flow path, particularly the coil group which is the heat generating portion.

(Embodiment) An embodiment of a cooling device for an optical deflector according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of an optical deflector according to the present invention. The same reference numerals as those shown in FIG. 5 which have already been used for the description of the conventional example indicate the same members, and thus detailed description thereof will be omitted.

The main difference between the present invention and the conventional example lies in the structure of the yoke and the ventilation port. That is, the yoke in the embodiment of the present invention
The yoke 30 is mounted in the lower end of the yoke body 8 in the radial direction so as to face the coil group 20, and a blade group 32 is provided on the lower surface of the yoke 30 so as to project therefrom. The blade group 32 may be formed by a cut and raised piece of the yoke 30. The number of the blade groups 32 corresponds to the number of poles of the flat magnet 16. Also, the yoke 30
A group of inflow ventilation holes 34 on the outer wall of the housing 2 in the radial direction with respect to the fixed shaft 10, that is, in the radial direction with respect to the fixed shaft 10, and a group of outflow ventilation holes on the bottom surface of the housing 2 in the thrust direction facing the blade group 32 Form 36.

Now, when the coil group 20 is energized and excited, the rotor 6 rotates in the housing 2 with the fixed shaft 10 as a core based on a known operating principle, the yoke 30 attached to the lower surface of the rotor body 8 together with the blade group 32. Since it rotates, the air in the housing 2 is caused to flow by the rotating action of the blade group 32. The air flowing from the light deflecting window 24 or the inflow ventilation port group 34 into the housing 2 in the arrow direction by the flow action flows in the housing 2 while flowing out from the ventilation port group 36 in the external arrow direction. The component arranged in the path, particularly the coil group 20 which is a heat generating portion, is cooled.

(Effect of the invention) The present invention has the following effects.

(B) The heat generated in the housing of the optical deflector without the hermetic structure is generated by the air blowing effect of the yoke including the blade group.
Since it can be discharged to the outside, the allowable input of the electric motor could be increased.

(B) If the yoke is fixed as in the conventional example, the eddy current loss during high-speed rotation of the rotor cannot be ignored, but in the present invention, the yoke can be rotated simultaneously with the disk-shaped magnet. , The loss is gone. However, if the blades provided on the yoke are made larger than the specified value, the wind loss increases, so it is optimal to design the size according to the speed of the optical deflector.

(C) The optical deflector is no longer hermetically sealed, and air flows through the housing, so that even if the lubricating oil becomes particulate, there is no risk of filling the inside.

(D) Since the number of blades is set to a number corresponding to the number of poles of the flat magnet, the torque fluctuation of the light deflection motor caused by the change in magnetic flux can be suppressed to a minimum, and the blade group can rotate efficiently with the rotor. The flow action of can be performed.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical deflector according to the present invention. FIG. 2A is a plan view of the yoke. FIG. 3B is a sectional view taken along the line AA ′ of FIG. FIG. 3 is a bottom view of FIG. FIG. 4 is a side view of FIG. FIG. 5 is a sectional view of a conventional optical deflector. 2 ... Housing, 4 ... Rotating polygon mirror, 6 ... Rotor, 8 ... Rotor body, 9 ... Flange, 10 ... Fixed shaft, 12, 14 ... Bearing, 1
6 ... Flat magnet, 18 ... Coil support plate, 20 ... Coil group, 24 ... Light deflection window, 30 ... Fixed yoke, 32 ... Blade group, 34
… Ventilation port group for inflow, 36… Ventilation port group for outflow.

Claims (4)

[Claims] 1. A yoke is provided at a lower end portion of a rotor body rotatably housed in a housing, and a blade group is projectingly provided on a lower surface of the yoke, and a ventilation port is provided in a radial direction of an outer periphery of the yoke and the blade group is provided. A cooling device for an optical deflector, which is formed by forming ventilation holes in the thrust direction facing each other. 2. A rotary polygon mirror is mounted on an upper surface of a flange of a rotor body, and a disk magnet is mounted on a lower surface of the rotor body, and between a yoke provided at a lower end of the rotor body and the disk magnet,
The cooling device for an optical deflector according to claim 1, wherein a coil supporting member having a coil group is disposed on the lower surface. 3. A cooling device for an optical deflector according to claim 1, wherein a radial inflow air vent group and a thrust direction outflow air vent group are formed in the outer circumference and the bottom surface of the housing, respectively. 4. A cooling device for an optical deflector according to claim 1, wherein the blade group protruding from the yoke has a number of blades corresponding to the number of poles of the flat magnet.